<!doctype html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport"
        content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <link rel="stylesheet" href="style.css">
</head>
<body>
  <div class="J_calculator">
    <div class="result">0</div>
    <div class="input-group">
      <input type="text" value="0" class="f-input" />
      <input type="text" value="0" class="s-input" />
    </div>
    <div class="btn-group">
      <button data-field="plus" class="current">+</button>
      <button data-field="minus">-</button>
      <button data-field="mul">*</button>
      <button data-field="div">/</button>
    </div>
  </div>

  <script src="main.js"></script>
</body>
</html>